1. Field of the Invention
For many years industry has been searching for a method and/or equipment to ensure that fugitive emissions from pumps, etc. were controlled. This control of undesirable fluid emissions is especially needed for the equipment, including pumps, vessels for batch materials, etc. where shafts exit a housing and any leakage around the exit and shaft is discharged into the atmosphere. It is also desirable, while preventing escape of said fluid emissions, to retain the fluids in the vessels or pumps without contamination from the exterior. This contamination matter may be fluid or solid. The provision of a seal, which would control emissions from the rotating equipment and prevent contamination into the equipment, is an object of this invention.
In the field of sealing it is desirable to have long life of the seal and total control of fugitive or other emissions, especially in this day of environmental concerns.
2. Related Art
Various forms of shaft sealing devices have been utilized to try to prevent the leakage of emissions from pumps, vessels having batch materials and/or other equipment utilizing rotating shafts which exit a housing. The housing will normally contain the material being pumped or mixed. The prior art has attempted to solve this problem of emission leakage, especially undesirable emissions by a variety of means, including sealless pumps, seals with liquid barriers and seals utilizing pressurized gasses such as air or nitrogen. The prior art has also attempted to solve the problem of emission leakage by introducing a seal having sealing members of different materials, such as carbon against ceramics. The prior art has also attempted to solve the problem of emission leakage by providing inert fluids between the rotor and the stator to minimize and improve the dissipation of the heat generated between the sealing faces, while not specifically and totally preventing the leakage of the materials. The prior art has utilized these various means to improve the emission control but has never provided for the positive removal and disposal of any contamination either by a liquid barrier or a pressurized gas. These prior devices did not remove the contaminations nor did they absolutely prevent the leakage of emissions.
The present invention utilizes controlled or uncontrolled absolute fluid pressures and controlled volumes of said pressures to ensure that any emissions leaking through the housing to the seal are removed to a proper disposal unit. This invention also provides an effective "dry running" mechanical seal utilizing the fluid pressures to minimize the frictional contact between sealing faces and indeed to control the frictional contact between the sealing faces.
The present invention utilizes a plurality of axial forces to effectively seal the equipment where the forces may be varied in strength without affecting the efficiency of the seal. The seal is also equally effective at any rotational velocity, and indeed performs in an identically predictable fashion as the rotational velocity is varied. This invention is also an excellent seal when emissions control are not necessary, i.e., no hazardous materials are involved, and will discharge into the atmosphere any leakage or debris which may be leaked into the seal.
This invention uses fluids, which may be air, gas, steam, and/or air-oil combinations which are introduced under pressure from an external source into the novel seal of this invention. The seal has a plurality of compartments formed within the chamber of the stationary member by a plurality of the sealing rings attached to the stationary member and the rotating members, including sealing faces. The stationary member also includes a separate passage for movement of fluid. The fluid is injected into the passage surrounding the rotating members and then is removed from the chamber through an outlet means, either to a recovery system or to the atmosphere.
This invention modifies the fluid pressure introduced to the chambers past the seal members and the rotational affect of the rotating members to produce and affect a pressure in a second chamber approximately one-half the fluid pressure introduced at the inlet.